A COSHH assessment for construction workers cannot be a generic form copied from a previous project. A groundworks gang cutting concrete, a decorating team spraying coatings and a maintenance operative using resin products may all work on the same site, but their exposures, controls and competence requirements are materially different. The assessment must reflect the task, substance, method of work and conditions actually present on site.
Under the Control of Substances Hazardous to Health Regulations 2002, employers must prevent exposure to hazardous substances where reasonably practicable. Where prevention is not possible, exposure must be adequately controlled. For principal contractors and contractors working under CDM 2015, this means COSHH arrangements need to connect directly with construction phase planning, RAMS, supervision, procurement and workforce training.
What a COSHH assessment must establish
A suitable COSHH assessment identifies the substances that could harm health, who may be exposed, how exposure occurs and which control measures are required. It should also confirm what happens if those controls fail, including first aid, spill response, emergency arrangements and health surveillance where applicable.
Construction sites create particular difficulties because the workface changes quickly. A product that is low risk when applied by brush in a ventilated area may create a significantly different exposure when sprayed, heated, mixed in volume or used inside a shaft, basement or other enclosed space. Site conditions, weather, ventilation, interface trades and work duration all affect the assessment.
The assessment must cover substances brought onto site in containers and substances generated by work activities. This distinction is frequently missed. A safety data sheet is useful evidence, but it is not a COSHH assessment. It describes the product’s hazards; it does not determine whether the planned controls are adequate for a particular task and location.
Common hazardous substances in construction work
Hazardous substances are not limited to clearly labelled chemicals. Construction teams can be exposed to dusts, fumes, vapours, mists, gases and biological agents as well as liquids, powders and pastes.
Respirable crystalline silica is a priority risk during cutting, chasing, drilling, grinding and demolition of concrete, mortar, stone and engineered materials. Controls may include specification of alternative materials or methods, wet cutting, on-tool extraction, suitably rated local exhaust ventilation, M-class or H-class vacuuming, exclusion zones and respiratory protective equipment selected through a proper face-fit process.
Other common exposures include cement and wet concrete, which can cause dermatitis and chemical burns; welding fume; wood dust; lead dust and paint during refurbishment; isocyanates in spray foam and coatings; epoxy resins and hardeners; solvents in paints, adhesives and cleaning products; and diesel engine exhaust emissions. Disturbance of older buildings can also introduce asbestos risk, which requires separate statutory control arrangements rather than a standard COSHH approach.
Some activities overlap with wider specialist requirements. Flammable paints, gases and solvents may require assessment under DSEAR as well as COSHH. Excavation, utility and confined-space works need coordinated consideration of hazardous atmospheres, ventilation, emergency rescue and permit controls. A COSHH document sitting separately from those arrangements will not provide defensible compliance.
How to complete a COSHH assessment for construction workers
Start with a live substance inventory for the project. This should include products held in stores, substances issued to work gangs, cleaning agents, fuels where relevant, materials supplied by subcontractors and substances generated during planned work. Procurement controls are essential: if site management does not know what is being ordered and delivered, it cannot assess or control exposure reliably.
For each substance or activity, obtain the current safety data sheet and identify the hazardous constituents, exposure routes and relevant workplace exposure limits. Then assess the task rather than the product in isolation. Consider how much is used, for how long, whether it is mixed, sprayed, heated, cut or abraded, the number of people nearby and the degree of enclosure.
The assessment should identify those at risk beyond the operative undertaking the task. Labourers, supervisors, adjacent trades, cleaners, visitors and members of the public can be exposed, particularly where dust or fume migrates. On a large project, planned sequencing and physical segregation may be more effective than relying on individuals to avoid another trade’s work area.
Apply the hierarchy of control
Personal protective equipment is not the starting point. The preferred approach is to eliminate the hazardous substance or process, substitute it for a less hazardous alternative, or change the work method so exposure is reduced at source. Examples include off-site cutting, pre-formed materials, low-silica products, brush application instead of spraying, or water suppression and extraction at the point of generation.
Where exposure remains, install and maintain engineering controls. These may include on-tool extraction, enclosed mixing systems, general mechanical ventilation or local exhaust ventilation. Equipment must be suitable for the contaminant and task, checked before use and subject to thorough examination and testing where required. A hired extraction unit with a damaged hose or blocked filter is not an effective control simply because it appears in the RAMS.
RPE should be the final layer, not the sole answer. Select it according to the hazard, concentration, duration and wearer. Tight-fitting RPE requires an adequate face-fit test for the specific make, model and size. Wearers must also be clean-shaven where the face seal contacts the skin. Disposable masks supplied without instruction, supervision or replacement arrangements are unlikely to demonstrate adequate control.
Make controls usable at the workface
A technically sound assessment fails if operatives cannot apply it during production pressure. COSHH controls should be translated into task-specific RAMS, toolbox talks, supervisor briefings and daily checks. Workers need to understand the health effect being prevented, the control they are expected to use and the signs that the control is not working.
For example, a silica control briefing should not merely instruct workers to wear a mask. It should specify the approved cutting method, required extraction or water suppression, housekeeping standard, exclusion arrangements, RPE type, pre-use checks and the action to take if visible dust is escaping. Dry sweeping and compressed-air cleaning should be explicitly prohibited where they can re-suspend hazardous dust.
Competence matters at every level. Operatives need practical instruction; supervisors need to recognise poor controls and stop work; site managers need confidence that subcontractors’ assessments are suitable and being implemented. Records of induction, briefings, face-fit testing, equipment inspections and corrective actions provide the evidence needed for internal assurance, client audits and regulatory inspection.
Health surveillance, monitoring and review
Where employees are exposed to substances linked with identifiable occupational disease and the work creates a reasonable likelihood of that disease, health surveillance may be required. This can apply to respiratory sensitisation, dermatitis, hand-arm vibration-related activities and certain other exposures depending on the risk. Occupational health provision should be based on the assessment, not offered as a substitute for exposure controls.
Air monitoring may also be necessary where it is not clear that exposure is adequately controlled, where there is a workplace exposure limit, or where the effectiveness of controls needs verification. Monitoring is particularly relevant for high-dust cutting, welding, lead work, spray application and processes conducted in enclosed or poorly ventilated areas. Results should lead to action, not simply be filed away.
COSHH assessments require review when there is reason to suspect they are no longer valid. On construction projects, that can mean a change in product, plant, task sequence, work location, workforce, supplier information or control method. They should also be reviewed after an incident, a report of ill health, an equipment failure, monitoring result or significant site inspection finding.
Documentation that stands up to scrutiny
Assessments should be clear enough for the workforce to use and detailed enough to demonstrate legal compliance. They need not repeat every line of a safety data sheet, but they should record the substance or process, hazards, people at risk, exposure routes, controls, PPE and RPE requirements, emergency actions, training needs, monitoring, health surveillance and review date.
For multi-contractor sites, the principal contractor should establish a consistent approval process for subcontractor COSHH information. This does not mean accepting a library of generic assessments at mobilisation. It means checking that substances have been declared, controls are compatible with site rules, tasks are adequately assessed and the required equipment, supervision and welfare arrangements are in place before work starts.
Evolution Safety Solutions can support contractors with task-specific COSHH assessments, DSEAR assessments, site audits and workforce training where projects require a documented, competent route to compliance.
The practical test is straightforward: if an operative starts the task tomorrow, can they identify the health hazard, access the correct control equipment and know when to stop work? If the answer is uncertain, the assessment needs further work before exposure becomes an incident or an occupational health claim.